London Fire Brigade’s group manager Rob Davies, who is at the scene, said: “This was a large grass fire and while Wanstead flats is an area of grass land, crews had to work very quickly to stop it from spreading.

“Smoke was making conditions very difficult for firefighters and causing a lot of disruption to local roads.

“Grass fires can embed into the ground and so while it is now smouldering, crews will be there into the night to keep damping down the earth.

“It can take a long time to properly stamp out a grass fire and while we expect to have crews at the scene for some time, we will reduce the levels of crews and equipment which will also help get roads moving again.

“We have attended over 20 grass fires this month as the hot weather has made the ground especially dry.

“If you see a grass fire, don’t attempt to put it out yourself as grass fires can travel very quickly and change direction without warning. Call the fire brigade and let us know where the fire is.”